Work vehicle

ABSTRACT

A work vehicle includes: a work implement; a cab having a front pillar located at the work implement side; a display unit provided along the front pillar, the display unit being configured to display work assistance information to be overlaid on an actual view of a work site; a display unit provided along the front pillar at a position different from the display unit, the display unit being configured to display work assistance information to be overlaid on the actual view of the work site; and a display controller configured to control displaying on the display units.

TECHNICAL FIELD

The present invention relates to a work vehicle including a head-up display.

BACKGROUND ART

Conventionally, various types of work vehicles have been known. Each of such work vehicles has a main body and a work implement connected to the main body.

Japanese Patent Laying-Open No. 2007-8284 (Patent Document 1) discloses a hydraulic excavator as an example of a work vehicle. In this hydraulic excavator, a film having a transmittance different from that of a front windshield of a cab thereof is adhered to the front windshield, thereby forming one display surface portion near the center of the front windshield. Moreover, visual information projected from a projection device provided in the cab is presented on this display surface portion.

CITATION LIST Patent Document

PTD 1: Japanese Patent Laying-Open No. 2007-8284

SUMMARY OF INVENTION Technical Problem

In Patent Document 1, the film having a transmittance different from that of the front windshield is adhered at the central portion of the front windshield as described above. Therefore, the central portion of the front windshield is inferior to a peripheral portion of the front windshield having no film adhered thereon, in terms of visibility for an actual view of a work site and a work implement.

Moreover, in the case of a configuration of displaying information at the central portion of the front windshield, the information may hinder the operator's manipulation for the work implement.

The present invention has been made in view of the above-described problem, and has an object to provide a work vehicle allowing for excellent visibility for an actual view of a work site or the like.

Solution to Problem

According to an aspect of the present invention, a work vehicle includes: a work implement; a cab having a front pillar located at the work implement side; a first display portion provided along the front pillar, the first display portion being configured to display first work assistance information to be overlaid on an actual view of a work site; a second display portion provided along the front pillar at a position different from the first display portion, the second display portion being configured to display second work assistance information to be overlaid on the actual view of the work site; and a display controller configured to control displaying on the first display portion and the second display portion.

Advantageous Effects of Invention

According to the invention above, there can be provided a work vehicle allowing for excellent visibility for an actual view of a work site or the like.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an external appearance of a work vehicle according to an embodiment.

FIG. 2 illustrates a configuration of a cab.

FIG. 3 is a block diagram showing a configuration of a control system included in the work vehicle.

FIG. 4 shows attachment positions of display units.

FIG. 5 illustrates an angle adjustment function of a combiner.

FIG. 6 illustrates details of the attachment positions of the display units.

FIG. 7 illustrates first exemplary displaying.

FIG. 8 illustrates second exemplary displaying.

FIG. 9 illustrates third exemplary displaying.

FIG. 10 illustrates sliding of the display units.

DESCRIPTION OF EMBODIMENTS

The present invention will now be described in an embodiment hereinafter with reference to the drawings. In the following description, identical components are identically denoted. Their names and functions are also identical. Accordingly, they will not be described repeatedly. It should be noted that in the following description, the terms “upward”, “downward”, “forward”, “rearward”, “left”, and “right” are based on an operator who sits on an operator's seat as a reference.

<A. General Configuration>

FIG. 1 is a diagram for illustrating an appearance of a work vehicle 101 according to an embodiment. In the present example, a hydraulic excavator will be described as an example of work vehicle 101 according to the embodiment as shown in FIG. 1.

Work vehicle 101 mainly includes a travel unit 1, a revolving unit 3, and a work implement 4. Work vehicle 101 has a main body composed of travel unit 1 and revolving unit 3. The main body has work implement 4 attached thereto. Travel unit 1 has a pair of right and left crawler belts. Revolving unit 3 is revolvably mounted to travel unit 1 via an upper revolving mechanism of travel unit 1. Revolving unit 3 has a cab 8 and the like.

Work implement 4 is pivotally supported at revolving unit 3 so as to be movable upward and downward and performs a work such as excavation of soil. Work implement 4 includes a boom 5, a dipper stick 6, and a bucket 7. Work implement 4 is provided at a right side relative to cab 8.

Boom 5 has a base movably coupled to revolving unit 3. Dipper stick 6 is movably coupled to the distal end of boom 5. Bucket 7 is movably coupled to the distal end of dipper stick 6. Bucket 7 is movable upward and downward relative to cab 8. Further, bucket 7 is also movable frontward and rearward relative to cab 8. Bucket 7 has teeth 7A.

<B. Display System in Cab>

FIG. 2 illustrates a configuration of cab 8. Particularly, FIG. 2 illustrates a display system 40 included in cab 8.

As shown in FIG. 2, cab 8 includes: a window 9; a front windshield 2 provided at window 9; two front pillars 91, 92; and a display device 70. Display device 70 includes a projection device 71, an optical lens system 72, and two display units 73, 74. Window 9 includes a window 9A and a window 9B below window 9A. Front windshield 2 includes a front windshield 2A provided at window 9A, and a front windshield 2B provided at window 9B.

Front pillar 91 is a left front pillar when viewed from the operator who sits on the operator's seat of cab 8. Front pillar 92 is a right front pillar when viewed from the operator. Moreover, front pillar 92 is at a position closer to work implement 4 than that of front pillar 91. It should be noted that each of front pillars 91, 92 is also referred to as “A-pillar”.

Front windshields 2A, 2B are disposed between front pillar 91 and front pillar 92. It should be noted that FIG. 2 shows a case where front windshield 2 is constituted of two glasses; however, front windshield 2 may be constituted of one glass.

Next, the following describes details of display system 40.

Projection device 71 is a projector. Optical lens system 72 is disposed between projection device 71 and each of display units 73, 74. Optical lens system 72 has a plurality of lenses. Part of the plurality of lenses of optical lens system 72 are movable along the optical axis.

Although details will be described later, each of display units 73, 74 functions as a head-up display that directly displays an image in the field of view of the operator. Each of display units 73, 74 is configured to display work assistance information to be overlaid on an actual view of a work site. Each of display units 73, 74 can be implemented using a combiner. Specifically, each of display units 73, 74 includes: a combiner (see combiners 731, 741 in FIG. 4); and an attachment member (see attachment members 732, 742 in FIG. 4) for attaching the combiner to front pillar 92. It should be noted that attachment positions of display units 73, 74 will be described later.

Each combiner is constituted of a half mirror which reflects a part of light and allows transmission of a remainder of the light therethrough. Each combiner reflects an image projected by projection device 71 to the operator side in cab 8 and allows transmission of light from the outside of cab 8 to the inside of cab 8 therethrough.

Thus, in display device 70, the operator can recognize the image projected on each combiner as a virtual image displayed to be overlaid on an actual view in front of cab 8.

<C. Configuration of Control System>

FIG. 3 is a block diagram showing a configuration of a control system included in work vehicle 101. As shown in FIG. 3, work vehicle 101 includes a manipulation device 10, a work implement controller 20, a work implement drive device 30, and a display system 40.

(c1. Manipulation Device 10)

Manipulation device 10 includes manipulation members 11L and 11R, a manipulation detector 12, a travel manipulation member 13, and a travel manipulation detector 14.

Manipulation members 11L and 11R are used for manipulations of work implement 4 and revolving unit 3. Specifically, manipulation member 11R is used by the operator to manipulate boom 5 and bucket 7. Manipulation member 11L is used by the operator to manipulate revolving unit 3 and dipper stick 6.

Manipulation detector 12 detects manipulations performed by the operator to manipulation members 11L and 11R.

Travel manipulation member 13 is used by the operator to control traveling of work vehicle 101. Travel manipulation detector 14 detects a manipulation performed by the operator to travel manipulation member 13. Work vehicle 101 is moved at a speed corresponding to an amount of the manipulation to travel manipulation member 13.

(c2. Work Implement Controller 20)

Work implement controller 20 includes a storage 21 and a processor 22. Storage 21 is composed of memory such as RAM (Random Access Memory) and ROM (Read Only Memory). Processor 22 is composed of a processing device such as a CPU (Central Processing Unit).

Work implement controller 20 mainly controls the operation of work implement 4 and the revolution of revolving unit 3. Particularly, work implement controller 20 generates a control signal for operating work implement 4 and revolving unit 3 in response to manipulations of manipulation members 11L and 11R. Work implement controller 20 outputs the generated control signal to work implement drive device 30.

(c3. Work Implement Drive Device 30)

Work implement drive device 30 has a proportional solenoid valve 31. Proportional solenoid valve 31 is operated based on a control signal issued from work implement controller 20. Proportional solenoid valve 31 supplies a hydraulic cylinder and a revolution motor with hydraulic oil at a flow rate corresponding to the control signal. As a result, work implement 4 operates and revolving unit 3 revolves.

(c4. Display System 40)

Display system 40 includes a bucket position detector 41, a display controller 43, and display device 70.

Bucket position detector 41 includes a bucket angle sensor 411, a dipper stick angle sensor 412, and a boom angle sensor 413.

Bucket angle sensor 411 detects a relative angle of bucket 7 from a predetermined reference position. Dipper stick angle sensor 412 detects a relative angle of dipper stick 6 from a predetermined reference position. Boom angle sensor 413 detects a relative angle of boom 5 from a predetermined reference position.

Bucket position detector 41 detects a position of bucket 7 with respect to the body of the work vehicle based on information of the three relative angles as detected. Particularly, the position of bucket 7 in the vehicular body coordinate system is detected. Bucket position detector 41 detects the position of teeth 7A of bucket 7, for example, as the position of bucket 7.

Display controller 43 causes various types of images to be displayed on display units 73, 74, such as information (work assistance information) for assisting a manipulation (work) of work implement 4 by the operator. Display controller 43 causes work assistance information (for example, a bar indicator indicating a distance between a design topography and teeth 7A) employing the detected position of bucket 7 to be displayed on display units 73, 74. Display controller 43 will be described more in detail as follows.

Display controller 43 has an image generator 431. Image generator 431 generates images to be displayed on display units 73, 74. Image generator 431 generates images representing a vehicular speedometer, an engine revolution indicator, a fuel indicator, a hydraulic temperature indicator, and the like. Further, image generator 431 generates images representing a plurality of pieces of work assistance information.

Particularly, image generator 431 is connected to a controller (not shown) that controls a motive power system of work vehicle 101. Image generator 431 receives information detected by various sensors, information regarding a content of control performed by the controller, and the like. Based on the received information, image generator 431 generates images to be displayed on display units 73, 74.

Display device 70 includes projection device 71, optical lens system 72, and display units 73, 74 as described above.

<D. Display Units>

FIG. 4 shows attachment positions of display units 73, 74. With reference to FIG. 4, display unit 73 and display unit 74 are provided at different positions along the front pillar. Each of display unit 73 and display unit 74 is disposed along front pillar 92 such that display unit 73 is located above display unit 74.

Particularly, display unit 73 includes combiner 731 and attachment member 732. Combiner 731 is attached to front pillar 92 by attachment member 732. Display unit 74 includes combiner 741 and attachment member 742. Combiner 741 is attached to front pillar 92 by attachment member 742. Moreover, each of combiners 731, 741 has no frame surrounding the outer edge thereof.

More particularly, attachment member 732 is attached to front pillar 92 at a position above attachment member 742. Accordingly, combiner 731 can be disposed above combiner 741 along front pillar 92.

As described above, two display units 73, 74, each of which serves as a head-up display, are disposed along front pillar 92 on top of each other in the upward direction and the downward direction. Therefore, decrease of visibility in the forward direction by the head-up displays when viewed from cab 8 can be reduced. Particularly, visibility at the central portion of front windshield 2 is not decreased. Therefore, work vehicle 101 has excellent visibility for the actual view of the work site or the like.

Further, since the head-up displays are disposed along front pillar 92 that is closer to work implement 4 than front pillar 91, an amount of eye movement of the operator during the manipulation of work implement 4 can be reduced as compared with a configuration in which the head-up displays are disposed along left front pillar 91. Moreover, since display unit 73 and display unit 74 are disposed at different positions (particularly, disposed on top of each other in the upward direction and the downward direction), the operator can check various types of information, such as work assistance information, by way of two display units 73, 73.

FIG. 5 illustrates an angle adjustment function of each of combiners 731, 741. As shown in FIG. 5, each of display units 73, 74 has a function of adjusting an inclination angle of its display surface relative to the horizontal plane (an angle adjustment function with which each display surface can be inclined in the forward direction and the rearward direction). Particularly, attachment members 732, 742 have mechanisms for rotating combiners 731, 741 in directions of arrows of the figure. As indicated by the arrows, in display unit 73, the upper and lower ends of combiner 731 can be revolved relative to the operator in the forward direction and the rearward direction. Likewise, as indicated by the arrows, in display unit 74, the upper and lower ends of combiner 741 can be revolved relative to the operator in the forward direction and the rearward direction.

Thus, each of display units 73, 74 is capable of vertical angle adjustments of combiners 731, 741. Therefore, the vertical angle of each display surface can be adjusted to an angle suitable for the operator.

An angle between the display surface of display unit 73 and the horizontal plane is preferably set to be larger than an angle between the display surface of display unit 74 and the horizontal plane. Particularly, an angle θ1 between a main surface of upper combiner 731 and horizontal plane H is preferably set to be larger than an angle θ2 between a main surface of lower combiner 741 and horizontal plane H (θ1>θ2). It should be noted that the term “main surface” refers to a surface to which an image from optical lens system 72 is projected.

According to this configuration, the display surface (main surface of combiner 741) of display unit 74 below display unit 73 is inclined more than the display surface (main surface of combiner 731) of display unit 73. Hence, visibility for a display content (work assistance information or the like) on each of display units 73, 74 can be improved as compared with a case where angle θ1 between the display surface of display unit 73 and horizontal plane H is smaller than angle θ2 between the display surface of display unit 74 and horizontal plane H (θ1<θ2).

FIG. 6 illustrates details of the attachment positions of display units 73, 74. As shown in FIG. 6, display unit 73 is disposed to be separated from display unit 74 by a distance d. Particularly, the attachment position of display unit 73 to front pillar 92 is separated, by distance d, from the attachment position of display unit 74 to front pillar 92.

Moreover, in work vehicle 101, each of the display surfaces of display units 73, 74 has a lateral width W smaller than distance d. Particularly, lateral width W of each of combiners 731, 741 is shorter than the interval (distance d) between the attachment position of display unit 73 and the attachment position of display unit 74. According to such a configuration, visibility in the forward direction when viewed from the cab (particularly, visibility at the central portion of front windshield 2) can be increased as compared with a configuration in which lateral width W is wider than the interval (distance d) between the attachment position of display unit 73 and the attachment position of display unit 74 (W>d).

Further, since each of combiners 731, 741 has no frame surrounding the outer edge of the display surface as described above, the display area can be larger than that in a hardware configuration having a frame (bezel) surrounding the outer edge of the display surface.

It should be noted that work implement 4, cab 8, front pillar 92, display unit 73, display unit 74, combiners 731, 741, and attachment members 732, 742 are examples of the “work implement”, “cab”, “front pillar”, “first display portion”, “second display portion”, “combiners”, and “attachment members” in the present invention, respectively.

<E. Exemplary Displaying>

Display system 40 has a plurality of display modes. Display system 40 receives selection of a display mode from the operator. Display system 40 controls a display content for each of display units 73, 74 in accordance with the received display mode.

The following describes display contents to be displayed on display units 73, 74 when there are such a plurality of display modes.

(e1. First Exemplary Displaying)

FIG. 7 illustrates first exemplary displaying. As indicated by states (A) and (B) in FIG. 7, display controller 43 causes work assistance information to be simultaneously displayed on display unit 73 and display unit 74.

Particularly, when a first display mode is set, display controller 43 causes the same work assistance information to be displayed on display unit 73 and display unit 74 as indicated by the state (A) in FIG. 7. For example, display controller 43 causes first work assistance information to be displayed on display unit 73, and causes second work assistance information, which is the same information as the first work assistance information, to be displayed on display unit 74. Meanwhile, when a second display mode is set, display controller 43 causes different pieces of work assistance information to be displayed on display unit 73 and display unit 74 as indicated by the state (B) in FIG. 7. For example, display controller 43 causes first work assistance information to be displayed on display unit 73, and causes second work assistance information, which is information different from the first work assistance information, to be displayed on display unit 74.

The state (A) of FIG. 7 represents an example in which a facing angle compass (image at each of the upper sides of display units 73, 74) and a cross section of a design topography and the teeth (image at each of the lower sides of display units 73, 74) are displayed as the first work assistance information and the second work assistance information that is the same information as the first work assistance information. It should be noted that the facing angle compass indicates whether or not work vehicle 101 directly faces the design topography data.

On the other hand, the state (B) of FIG. 7 represents an example in which a bar indicator (image at the left side of display unit 74) and distance information (image at the right side of display unit 74) indicating a distance between the design topography and teeth 7A are displayed as the second work assistance information that is information different from the first work assistance information. The bar indicator graphically indicates the distance between the design topography and teeth 7A.

As described above, when the first display mode is set, display controller 43 causes the same work assistance information to be simultaneously displayed on display unit 73 and display unit 74. According to this configuration, when checking the work assistance information, the operator can obtain the information by checking displaying on one of display unit 73 and display unit 74 involving a smaller amount of eye movement.

Moreover, when the second display mode is set as described above, display controller 43 causes the different pieces of work assistance information to be simultaneously displayed on display unit 73 and display unit 74. According to this configuration, display system 40 can display a larger number of types of work assistance information as compared with the case where the first display mode is set. Therefore, the operator can visually recognize a larger number of pieces of information simultaneously as compared with the case where the first display mode is set.

(e2. Second Exemplary Displaying)

FIG. 8 illustrates second exemplary displaying. As indicated by states (A) and (B) in FIG. 8, display controller 43 causes the work assistance information to be displayed on one of display unit 73 and display unit 74.

Particularly, when a third display mode is set, display controller 43 causes the work assistance information to be displayed on only display unit 73 of display unit 73 and display unit 74 as indicated by the state (A) in FIG. 8. On the other hand, when a fourth display mode is set, display controller 43 causes the work assistance information to be displayed on only display unit 74 of display unit 73 and display unit 74 as indicated by the state (B) in FIG. 8.

It should be noted that as indicated by the states (A) and (B) of FIG. 8, the work assistance information displayed on display unit 73 when the third display mode is set is the same (particularly, the same type of information) as the work assistance information displayed on display unit 74 when the fourth display mode is set.

As such, when the third display mode or the fourth display mode is set, display controller 43 causes the work assistance information to be displayed on one of display unit 73 and display unit 74. According to such a configuration, electric power consumed by display system 40 can be reduced in display system 40.

(e3. Third Exemplary Displaying)

FIG. 9 illustrates third exemplary displaying. As indicated by states (A) and (B) in FIG. 9, in accordance with a position of bucket 7, display controller 43 determines whether to display the work assistance information on display unit 73 or display unit 74.

When the position of bucket 7 is higher than a predetermined position, display controller 43 causes the work assistance information to be displayed only on display unit 73 of display unit 73 and display unit 74. On the other hand, when the position of bucket 7 is lower than the predetermined position, display controller 43 causes the work assistance information to be displayed only on display unit 74 of display unit 73 and display unit 74. It should be noted that the position of bucket 7 is typically specified as the position of teeth 7A of bucket 7.

Particularly, when the position of bucket 7 is changed from a position higher than the above-described predetermined position to a position lower than the above-described predetermined position, display controller 43 switches the display unit for displaying the work assistance information from display unit 73 to display unit 74 therebelow. On the other hand, when the position of bucket 7 is changed from a position lower than the above-described predetermined position to a position higher than the above-described predetermined position, display controller 43 switches the display unit for displaying the work assistance information from display unit 74 to display unit 73 thereabove.

According to such a configuration, when the operator checks the work assistance information, the eye movement of the operator can be reduced as compared with a configuration in which the work assistance information is displayed only on display unit 74 when the bucket is at a position higher than the predetermined position. On the other hand, when the operator checks the work assistance information, the eye movement of the operator can be reduced as compared with a configuration in which the work assistance information is displayed only on display unit 73 when the bucket is at a position lower than the predetermined position.

<F. Modification>

(1) Each of display unit 73 and display unit 74 may be attached to front pillar 92 so as to be slidable along an extending direction of front pillar 92.

FIG. 10 illustrates sliding of display units 73, 74. As shown in FIG. 10, the operator can slide combiner 731 along the extending direction of front pillar 92 by sliding attachment member 732 of display unit 73 along the extending direction of front pillar 92. Moreover, the operator can slide combiner 741 along the extending direction of front pillar 92 by sliding attachment member 742 of display unit 74 along the extending direction of front pillar 92.

According to such a configuration, the operator can set the attachment position of each of display unit 73 and display unit 74 at his/her desired height.

It should be noted that in the case of such a configuration, when each of the attachment positions of display units 73, 74 is changed, the position to which the image such as the work assistance information is projected needs to be changed in accordance with the change of each of the attachment positions of display units 73, 74. Control for the position to which the image is projected may be performed based on the operator's manipulation or may be performed automatically.

When the control for the position to which the image is projected is performed automatically, display system 40 may be configured such that display controller 43 obtains information of each of the attachment positions of display units 73, 74 (particularly, coordinates of each of combiners 731, 741), and controls, based on the obtained information, the position to which the image such as the work assistance information is projected. It should be noted that the information (for example, height information) of each of the attachment positions may be obtained based on analysis of image data obtained by image capturing with a camera (not shown), or the information of each of the attachment positions may be obtained using a sensor (not shown). A method for obtaining the information of each of the attachment positions of display units 73, 74 is not limited in particular.

(2) Each of display unit 73 and display unit 74 is preferably detachably attached to front pillar 92. According to such a configuration, there can be employed a configuration having only one display unit, for example. Moreover, this configuration is excellent in terms of maintenance for the display unit, as compared with a configuration in which the display unit cannot be detachably attached to front pillar 92.

(3) In the above-described embodiment, work vehicle 101 configured to include the two display units has been illustratively described. Specifically, it has been illustratively described that display system 40 is configured to include two combiners 731, 741. However, each of the number of display systems and the number of combiners is not limited to two and may be more than or equal to three.

(4) In the description above, display units 73, 74 configured to respectively include combiners 731, 741 have been illustratively described; however, the configuration is not limited thereto.

For example, there may be employed the following configuration: the operator visually recognizes an image projected on a film, rather than a virtual image. Specifically, a first film permitting transmission of incoming external light to cab 8 therethrough may be used instead of display unit 73, and a second film permitting transmission of incoming external light to cab 8 therethrough may be used instead of display unit 74.

It should be noted that each of the first film and the second film is disposed along front pillar 92 such that the first film is located above the second film. In this case, the first film and the second film function as head-up displays. It should be noted that the first film and the second film are examples of the “first display portion” and “second display portion” in the present invention.

In the case of such a configuration, the operator of cab 8 can visually observe an actual view of a work site including work implement 4 through the first film or the second film. Therefore, also in the case of such a configuration, visibility at the central portion of the front windshield is not decreased by the head-up displays. Therefore, work vehicle 101 is excellent in visibility for the actual view of the work site or the like.

Moreover, there may be employed the following configuration: the operator directly visually recognizes an image displayed on a display, rather than a virtual image. Specifically, a transparent first display (for example, a transmission type liquid crystal display) permitting transmission of incoming external light to cab 8 therethrough may be used instead of display unit 73, and a transparent second display permitting transmission of incoming external light to cab 8 therethrough may be used instead of display unit 74.

It should be noted that each of the first display and the second display is disposed along front pillar 92 such that the first display is located above the second display. In this case, the first display and the second display function as head-up displays. It should be noted that the first display and the second display are examples of the “first display portion” and the “second display portion” in the present invention.

Also in this case, visibility at the central portion of the front windshield is not decreased by the head-up displays as with the cases where combiners 731, 741 are used and the first film and the second film are used. Therefore, work vehicle 101 is excellent in visibility for the actual view of the work site.

The embodiments disclosed herein are illustrative and are not limited to only the content above. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

REFERENCE SIGNS LIST

1: travel unit; 2: front windshield; 3: revolving unit; 4: work implement; 5: boom; 6: dipper stick; 7: bucket; 7A: teeth; 8: cab; 10: manipulation device; 20: work implement controller; 40: display system; 43: display controller; 70: display device; 71: projection device; 72: optical lens system; 73, 74: display unit; 91, 92: front pillar; 101: work vehicle; 731, 741: combiner; 732, 742: attachment member; H: horizontal plane; L: central line. 

1. A work vehicle comprising: a work implement; a cab having a front pillar located at the work implement side; a first display portion provided along the front pillar, the first display portion being configured to display first work assistance information to be overlaid on an actual view of a work site; a second display portion provided along the front pillar at a position different from the first display portion, the second display portion being configured to display second work assistance information to be overlaid on the actual view of the work site; and a display controller configured to control displaying on the first display portion and the second display portion.
 2. The work vehicle according to claim 1, wherein the first display portion is provided above the second display portion, the work implement includes a bucket, and the display controller is configured to cause the first work assistance information to be displayed on the first display portion without causing the second work assistance information to be displayed on the second display portion, when a position of the bucket is higher than a predetermined position, and cause the second work assistance information to be displayed on the second display portion without causing the first work assistance information to be displayed on the first display portion, when the position of the bucket is lower than the predetermined position.
 3. The work vehicle according to claim 1, wherein each of the first display portion and the second display portion has a combiner, and an attachment member configured to attach the combiner to the front pillar.
 4. The work vehicle according to claim 1, wherein each of the first display portion and the second display portion has a function of adjusting an inclination angle of a display surface relative to a horizontal plane.
 5. The work vehicle according to claim 1, wherein an angle between a display surface of the first display portion and a horizontal plane is larger than an angle between a display surface of the second display portion and the horizontal plane.
 6. The work vehicle according to claim 1, wherein the first work assistance information and the second work assistance information are the same information.
 7. The work vehicle according to claim 1, wherein the display controller is configured to simultaneously display the first work assistance information and the second work assistance information.
 8. The work vehicle according to claim 1, wherein each of the first display portion and the second display portion is attached to the front pillar so as to be slidable along an extending direction of the front pillar.
 9. The work vehicle according to claim 1, wherein each of the first display portion and the second display portion is detachably attached to the front pillar.
 10. The work vehicle according to claim 1, wherein each of a lateral width of a display area of the first display portion and a lateral width of a display area of the second display portion is smaller than an interval between an attachment position of the first display portion to the front pillar and an attachment position of the second display portion to the front pillar.
 11. The work vehicle according to claim 1, wherein each of the first display portion and the second display portion has no frame surrounding an outer edge of a display surface. 